1. Field of the Invention
This invention relates to a system for regulating the movement of a door, and more particularly, to a system for automatically and controllably closing a sliding door.
2. Description of the Prior Art
Many contemporary homes include sliding glass doors. For the sake of convenience and energy conservation, it is desirable to provide sliding doors with the ability to close automatically. Although several devices have been proposed for automatically closing sliding doors, such devices have failed to provide an inexpensive, easily installed system or kit for controllably closing a sliding door in a relatively slow manner and for maintaining the ease and ability of a person to open the sliding doors unhindered.
For example, U.S. Pat. No. 4,649,598, issued to Kinsey, et al., discloses a door closer with a sliding door. Kinsey includes a long cylindrical housing attached to one vertical edge of the sliding door, a weight in the cylinder and a cable connecting the weight over a pulley in the top of the cylinder to an anchor in the door jam. A seal surrounds the weight so that there is a sealing contact with the housing to form a pneumatic cylinder therein. The lower part of the cylinder is provided with passageways which let air go in or out of the cylinder. The upper part of the weight is provided with a valve which is always biased to the open position but is held closed so long as the cable is taut. When the cable is loose, the valve opens and air can rush out and the door will close faster. As illustrated clearly in FIGS. 3 and 11, Kinsey requires a rather complicated spring-biased pneumatic valve in addition of other fairly complex components, which are relatively expensive and may become unreliable during extended use.
Similarly, U.S. Pat. No. 4,126,912 issued to Johnson, discloses a kit of components readily attachable to a sliding door without modification of the door to effect gravity actuated closing. Johnson discloses a guide channel and pulley that are simply adhesively secured on outwardly facing surface portion of door at the rear of the door. A weight is slidably confined within the guide and hangs from a line entrained over the pulley and connected to a hook on the doorway lintel. The kit includes a universal wheel and bracket assembly that can be readily mounted on many different types of doors. Johnson does not appear to disclose any means of damping, regulating, or controlling the rate associated with the automatic closing of the sliding door. Johnson also appears to require the use of anti-friction devices to minimize door friction and provide optimum operation.
Another reference showing an automatic door or window closing device is U.S. Pat. No. 4,884,369 issued to Tatham. Tatham includes a tube attached to the edge of a movable door or window. The tube has a weight displaced therein with a cable attached at the top which passes out of the top of the tube across a pulley and is connected to the door or window jam. A pneumatic seal is provided between the weight and the inside wall of the tube and works in conjunction with the port and valve at the bottom of the tube for controlling the flow of air passing there- through. When the door or window is opened, the weight rises in the tube. When the door or window is released, the weight drops in the tube according to the adjustment of the port and the valve at the bottom of the tube until the door or window is completely closed. Tatham requires a pneumatic seal between the weight and the tube used in conjunction with a relatively complicated port means below the weight. This arrangement appears to be relatively complicated, precise, expensive, and unreliable.
Another reference disclosing a door closing device is U.S. Pat. No. 4,665,584 issued to Williams. Williams describes a device having an upright tube closed at the bottom and containing a damping liquid with a sinker weight being arranged in the tube and connected to a flexible cord which extends out of the top of the tube for connection to a door so that a door is automatically closed when released, the sinker weight falling under gravity to pull the door closed. The device includes a passage extending through the sinker weight with a valve seat formed at the lower end of the passage and cooperating with a self-seating valve member (preferably a plastic ball which is not captive relative to the weight) which controls liquid flow through the passage when the weights sinks. As the door is opened, the weight is pulled rapidly upwards and lifts off the buoyant valve member. Preferably, the valve member substantially seals the passage in the weight and there is a clearance around the weight for passage of the damping liquid during closing of the door. A difficulty of Williams is that it relies upon the clearance fit between the weight and the tube to provide uniform damping of the closing door motion, since the loading valve member substantially seals the passage in the weight when the weight sinks. Thus, the Williams device appears to be difficult to adapt for use in the a variety of door closing applications. Also, the casting of the weight is more complicated since it must provide for the formation of a bore hole through the weight and of a relatively precise valve seat for receiving the buoyant valve member.
U.S. Pat. No. 4,891,911, issued to Young describes an automatic door closing device comprising an elongated tubular member containing a counter weight that maintains an airtight seal as it moves up and down within the tubular member. A flexible cable attached at one end to the counter weight is anchored at its opposite end to an upper track member at a pre-selected location. An upper end element fits into the tubular member and has a pulley wheel for supporting the cable between its ends. A lower end element that fits into the lower end of the tubular member forms an airtight seal for a variable chamber below the counter weight. This lower end element has a check valve for allowing outside air to flow into the chamber while preventing air from flowing out of the chamber and it also supports a separate, adjustable bleed valve for allowing air to flow out of the chamber at a restricted rate so as to control the downward travel of the cable within the tubular member when the door is closing. Hence, Young also requires relatively complicated, expensive, and unreliable pneumatic components.
The foregoing limitations and difficulties in the art generally indicate that it would be desirable to provide an inexpensive, simple, reliable, easily installed system or kit for automatically closing a door in a controlled manner while also maintaining the ease and ability of opening the door in a substantially unhindered fashion.